U.S. Pat. No. 4,245,869 describes an electromagnetic bearing including a rotor element secured to the rotary mobile to be supported, and a stator element including eight cores, each core being equipped with a drive coil, and a detection coil. It is particularly advantageous for the position detectors to be associated with the bearing itself, because, in this way, the position of the mobile is measured in the plane of action of the forces due to the drive coils of the bearing. Furthermore, by using such a disposition it possible to reduce the size and the cost of the functions of suspension and position detection.
However, in that document, the four drive coils of the bearing on each of the X and Y axes are all powered together in series and not separately in pairs, so that the rotor being off-center cannot be corrected.